Polymers are candidates for use as inter-level and intra-layers dielectric materials in integrated circuits (ICs) and as bonding layers in packaging applications and in three-dimensional integration (3-D) of ICs. Polymer materials are typically poor thermal conductors and as a result act a thermal barrier to heat flow to more thermally conducting layers or structures. In addition polymers commonly suffer from thermal stability problems when the dielectric is heated during subsequent processing of the integrated circuit or during packaging.
In the inter-level and intra-level dielectic applications of polymers, candidate materials should possess a low dielectric constant (k) in order to minimize the impact of capacitive coupling on the performance of the IC especially as IC dimensions are reduced through scaling. Often the polymer chains are modified to add chemical functional groups such as fluorine to lower their k. Due to the higher level of fluorine content in such candidate low-k polymers such as bisbenzocyclobutene (BCB), perfluorocyclobutane (PFCB), poly(tetrafluoroethylene) (PTFE), adhesion to prior and subsequent layers is often a problem.
As IC feature sizes are scaled to smaller dimensions and the ICs operate at higher frequencies, devices are projected to generate more heat and subsequently experience higher temperatures during operation. As a result, the thermal conductivity of polymers used as inter-level and intra-level dielectrics and as adhesives for bonding and mounting should be improved in order to conduct heat away from the integrated circuit.